Managing soil organic matter amendment and microbial community structure to enhance soil heating during solarization

1438694(VanderGheynst)。使用包括甲基溴、1，3-二氯丙烯和氯苦在内的合成化学品进行土壤熏蒸是控制土壤害虫的有效做法。然而，它也会导致大气中挥发性有机化合物的积累，导致严重的空气污染。有毒土壤熏蒸的一种有希望的替代方法是将有机土壤改良剂与土壤日晒相结合，在土壤中覆盖一层透明的塑料薄膜，导致土壤被动太阳能加热和土壤传播的病原体灭活。虽然将土壤改良剂与日晒相结合是非常有效的，但它并没有被广泛使用，因为目前的做法需要在许多作物生产期间进行处理。这项研究的基础是，如果种植者能够在不损失产量的情况下采用这种做法，改良土壤的日晒将得到更广泛的利用。建议开展两项研究工作，以更好地利用日晒技术：1)探索提高土壤温度的有机质改良剂技术，从而减少日晒所需时间，并允许在生产非高峰期进行处理；2)阐明微生物群落对日晒过程中有机质分解和土壤加热的贡献。了解有机质分解、群落结构和有机酸积累之间的相互作用，将使农民在管理土壤有机质和加强日晒的微生物群落修正方面做出更明智的决定。验证实验将是针对加州大学合作推广教育工作者的示范活动的一部分，以便从项目中获得的信息得到传播，并随时应用于造福整个社会。此外，这项研究的结果将成为由PI指导的GK-12计划中六年级课程和活动的一部分。该项目将博士生与六年级教师配对，开发和教授与可再生能源和环境可持续发展相关的STEM课程。课程和活动将包括短波和长波辐射对土壤加热和巴氏杀菌的影响。一旦在课堂上进行了测试，并得到了老师的反馈，课程将被提交到TeachEngineering ering.org。学生的培训将是高度跨学科的工程学和生物学。总体方法包括1)实验，研究如何调整有机质组成和微生物群落接种，以促进土壤中高温发酵相关的热量产生；2)微生物群落动力学的深入表征；以及3)实验室和现场验证实验。土壤加热研究将首先使用温度控制培养箱中的实验室土柱进行。这将允许研究有机质土壤改良剂在何种条件下刺激好氧微生物活动，从而促进代谢加热。为了阐明微生物群落在土壤加热中的作用，将改变接种物的组成和土壤因素，并使用提取的DNA的高通量测序来测量由此产生的群落动态。支持植物生长的土壤适宜性将使用植物毒性分析进行评估。将完成田间研究，以确认实验室结果，并进一步研究有机质改良剂和初始微生物群落结构对土壤加热和盐化土壤的植物毒性的影响。提出的这项研究将加深对土壤日晒过程中微生物活动动态和相关土壤加热的理解。初步数据表明，用有机质修饰的群落提高了土壤中的生物活性，然而，关于这些群落的时空变化以及它们如何促进有机质分解和有机酸的产生造成植物毒性，人们知之甚少。下一代高通量测序将提供对土壤日晒过程中微生物群落动态的基本洞察，以及微生物群落在日晒过程中土壤加热中所起的作用。

1438694 (VanderGheynst). Soil fumigation with synthetic chemicals including methyl bromide, 1,3-dichloropropene, and chloropicrin, is an effective practice for controlling soil borne pests. However, it also results in accumulation of volatile organic compounds in the atmosphere, contributing to significant levels of air pollution. A promising alternative to toxicant-based soil fumigation involves combining organic soil amendments with soil solarization, in which soil is covered with a transparent plastic film, resulting in passive solar heating of the soil and inactivation of soilborne pathogens. Although combining soil amendments with solarization is very effective, it is not widely used because current practices require treatment during the time in which many crops are produced. The basis of this research is that solarization of amended soil would be utilized more widely if growers could adopt the practice without losing production. It is proposed that two lines of investigation might contribute to greater utilization of solarization: 1) exploration of techniques involving organic matter amendment that increase soil temperature, thereby reducing the time required for solarization and allowing treatment during off-peak production periods; and 2) elucidation of the contributions of microbial communities to organic matter decomposition and soil heating during solarization. Knowledge of the interaction between organic matter decomposition, community structure and organic acid accumulation will allow farmers to make more informed decisions on managing soil organic matter and microbial community amendment for enhanced solarization. Validation experiments will be part of demonstration activities directed towards UC Cooperative Extension educators so that the information gained from the project is disseminated and readily applied to benefit society at large. Also, the results from this research will become part of a 6th grade lesson and activity in the GK-12 program directed by the PI. This program pairs PhD students with 6th grade teachers to develop and deliver STEM curriculum related to renewable energy and environmental sustainability. The lesson and activity will incorporate the effects of short and long-wave radiation on thermal heating and pasteurization of soil. Once tested in classrooms with feedback from teachers, the lesson will be submitted to TeachEngineering.org. Student training will be highly interdisciplinary in engineering and biology.The overall approach to be pursued involves 1) experiments that examine how organic matter composition and microbial community inoculum can be tailored to facilitate heat generation associated with thermophilic fermentation in soil, 2) an in-depth characterization of microbial community dynamics, and 3) laboratory and field validation experiments. Soil heating studies will be conducted first using laboratory soil columns in temperature-controlled incubators. This will allow investigation conditions under which organic matter soil amendments stimulate aerobic microbial activity, and therefore metabolic heating. To elucidate the role of the microbial community on soil heating, inoculum composition and soil factors will be varied and the resulting community dynamics measured using high-throughput sequencing of extracted DNA. Soil amenability for supporting plant growth will be assessed using phytotoxicity assays. Field studies will be completed to confirm laboratory results and further investigate the effects of organic matter amendment and initial microbial community structure on soil heating and phytotoxicity of solarized soil. This research proposed will improve understanding of microbial activity dynamics and associated soil heating during soil solarization. Preliminary data indicate communities amended with organic matter enhance the rate of biological activity in the soil, however, little is known about the spatial and temporal changes in these communities and how they contribute to organic matter decomposition and production of organic acids that cause phytotoxicity. Next generation high-throughput sequencing will provide fundamental insight into the microbial community dynamics during soil solarization, and the role microbial communities play in soil heating during solarization.